This invention relates to a two-color copying machine which carries out a two-color heat-sensitive recording operation based on the principle that a recording sheet has different coloring temperatures.
A two-color copying machine for recording an image in two colors, e.g. black and red, according to an electrostatic photographic technique is known in the art. In such a conventional two-color copying machine, two electrostatic recording drums or sheet members are used, and electrostatic latent images are formed thereon respectively. The latent images thus formed are then developed with the black and red toners, respectively. The two toner images thus obtained are transferred onto the recording sheet in such a manner that they are not displaced relative to each other. The toner images are then thermally fixed, to obtain the desired image on the recording sheet. This conventional two-color copying machine can make a number of copies of an original by repeatedly exposing the original to light; however, it is disadvantageous in that it consumes a large electric power in order to fix the toner images on the recording sheet. Furthermore, since an extremely large amount of heat is generated by the fixing unit, it is necessary to provide a heat insulation mechanism in order to protect other circuits and components from the heat, which increases the size of the copying machine and the manufacturing cost. For these reasons, the conventional two-color copying machine is disadvantageous.